On the test, the number of questions that Rosalie answered correctly was 45. What was the percentage of all the questions on the test that Rosalie answered correctly?
(1) The number of questions that she left unanswered was 15.
(2) The number of question on the test was 114.
The Statement (1) by itself will not help us to answer the question, since we do not know how many questions she answered wrongly, because only then can we know the total number of questions on the test. The number of questions on the test was necessary for working out the percentage.
So, (A) can not be the answer
But From (2) alone we can say that the percentage of questions that she answered correctly was [45/114] * 100.